Radiation-resistant high molecular composition

ABSTRACT

A radiation-resistant high molecular composition is disclosed, charqacterized in that, to the high molecular polymer, a halogenated acenaphtylene and/or condensates thereof represented by a following general formula [I] ##STR1## (wherein, X indicates a chlorine or bromine atom, a indicates 0 to 2, b indicates 1 to 6 and n indicates an integer not less than 1) and a diphenyl ether derivative represented by a following general formula [II] ##STR2## (wherein, R 1  and R 2  indicate any ones of hydrogen atom, alkyl, alkoxy, phenyl phenoxy, diphenyloxy and terphenyloxy group) and/or basic lead compound are formulated.

This is a division of application Ser. No. 07/098,883, filed on Sept.21, 1987 U.S. Pat. No. 4,900,766.

BACKGROUND OF THE INVENTION

The present invention relates to a high molecular composition, theradiation resistance being improved drastically, and an electric wire orcable used said high molecular composition as a covering material.

Organic high molecular materials used for nuclear reactors, breederreactors, treatment facilities of radioactive wastes, ionizing radiationgenerator or the like, for example, electric wires, cables and variousinstruments are always exposed to radiation to a considerable extent.

Such high molecular materials having been subjected to the exposure ofhigh doses of radiation in the air generally become hard and brittle tolose the pliability and to weaken, so that the characteristics thereofare lowered remarkably.

For this reason, high degree of radiation resistance is requested forthe high molecular compositions used for the covering and insulatingmaterials of electric wires, cables, etc., packings, seal materials,frames, hose materials, etc. having such purpose of use from thestandpoints of economics and safety, and the researches on thetechnology to provide the radiation resistance to high molecularmaterials are advancing.

It has been known that, by formulating a halogenated acenaphthyleneand/or condensates thereof represented by a following general formula[I] ##STR3## (wherein X indicates a chlorine or bromine atom, aindicates 0 to 2, b indicates 1 to 6 and n indicates an integer not lessthan 1) to the high molecular polymer, high degree of radiationresistance and excellent fire resistance can be provided to the highmolecular polymer (Japanese Patent Publication No. Sho 58-1146 and Sho60-25063).

When formulating said halogenated acenaphthylene and/or condensatesthereof to the high molecular polymer, said halogenated acenaphthyleneand/or condensates thereof are used usually by allowing to melt anddisperse into the high molecular polymer by heating at the time ofkneading or thermal molding.

As an another method, utilizing the radical polymerization reaction ofdouble bond between carbon 1 and carbon 2 of halogenated acenaphthyleneunit, free radical-generating treatment is carried out after the moldingto graft onto the high molecular polymer. It is known that theimprovements in the radiation resistance and the fire resistance of highmolecular polymers can be achieved by these methods.

As a result of investigations on the effect of provision of radiationresistance to the high molecular polymer by the use of halogenatedacenaphthylene and/or condensates thereof, the inventors have found thatthere occurs a significant difference in the development of radiationresistance depending upon the fluctuation of processing conditions,difference in quality of halogenated acenaphthylene and/or condensatesthereof and the like.

Namely, when the halogenated acenaphthylene and/or condensates thereofwere formulated to polyolefinic resins, rubbers, etc., if the processingtemperature was lower than the melting temperature of halogenatedacenaphthylene and/or condensates thereof, or if the condensationcomposition of condensates of halogenated acenaphthylene was high, sucha phenomenon that the elongation ratio at the fracture point being ajudging criterion of radiation resistance was lowered was recognizedresulting in the problem.

Moreover, in consequence of the investigations on the application ofhigh molecular compositions formulated the halogenated acenaphthyleneand/or condensates thereof to the use for a nuclear reactor, that thehot-water resistance proved poor. Namely, when these high molecularcompositions were exposed to the high-temperature steam of 150° C. formore than 24 hours, the mechanical properties were kept, but the sheetswelled and that the electric properties, in particular, the dielectricbreakdown voltage was lowered.

In addition, when formulated to crosslinked polyethylene, there weresuch problems that the crosslinking of polyethylene was hindered not toraise the gel fraction and to cause a decrease in the deformationtemperature under heat and such processing problems that the surface ofsheet was roughened at the time of press molding and the like.

Furthermore, as a designing standard of nuclear power station, loss ofcoolant accident (LOCA) is established. The requirement matter statesthat it is necessary for the high molecular polymers to retain theirgood electric characteristics even if exposed to heated steam or hotwater after the exposure to radiation. However, with those of which theelongation ratio at the fracture point was lowered after the exposure toradiation as described above, it was also recognized that the electriccharacteristics were lowered after the exposure to steam. In otherwords, even after bromine was eliminated through the exposure toradiation and the brominated acenaphthylene and/or condensates thereofbecame to a stabilized state, the phenomenon that the electriccharacteristics were lowered remarkably by super heated steam or hotwater was recognized to become a problem.

The purpose of the present invention is to provide a high molecularcomposition stably developable the high-degree of radiation resistance,hot-water resistance and excellent electric characteristics after theLOCA test by being not subjected to the influence of fluctuation ofprocessing and molding conditions and by suppressing the influence ofquality of halogenated acenaphthylene and/or condensates thereof.

In view of these problems of the prior art, the inventors made diligentinvestigations on the method of developing the radiation resistance ofhigh molecular composition formulated the halogenated acenaphthyleneand/or condensates thereof. As a result, the inventors have found that,depending on the processing and molding conditions and the difference inthe quality of halogenated acenaphthylene and/or condensates thereof,the dispersibility and the compatibility in the high molecular polymerdiffer subtly to affect significantly on the development of variouscharacteristics.

In order to solve this problem, the inventors energetically searched foradditives not affecting adversely on the physical properties of the highmolecular compositions, such as an improver of dispersibility to improvethe dispersibility of halogenated acenaphthylene and/or condensatesthereof, and a trapping agent of hydrogen halide formed byde-halogenation.

As a result, various kinds of high molecular resins, rubbers, esterplasticizers, paraffinic and aromatic process oils, variouslubricants,.etc. proved to hardly improve the dispersibility and, in thecase of the formulation of metal oxides such as zinc white, magnesiumoxide, antimony trioxide, etc. caused swelling by hot water and did notprevent the lowering in electric characteristics.

SUMMARY OF THE INVENTION

The inventors have found that, when formulating a diphenyl etherderivative represented by a following general formula [II] ##STR4##(wherein, R₁ and R₂ indicate any ones of hydrogen atom, alkyl, alkoxy,phenyl, phenoxy, diphenyloxy and terphenyloxy gorup) and/ or basic leadcompound to the high molecular polymer in appropriate amount in additionto the halogenated acenaphthylene and/or condensates thereof representedby the following general formula [I] ##STR5## (wherein, X indicates achlorine or bromine atom, a indicates 0 to 2, b indicates 1 to 6 and nindicates an integer not less than 1), the dispersibility in the highmolecular polymer of halogenated acenaphthylene and/or condensatesthereof is improved remarkably and specifically and the radiationresistance and various characteristics of the high molecular compositionare enhanced to develop stably.

Further, the formulation of these diphenyl ether derivatives and/orbasic lead compounds have been found not to affect adversely on thecrosslinking characteristics of high molecular polymer and also on theelectric and mechanical characteristics leading to the completion of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a photograph showing the dispersibility of brominatedacenaphthylene condensates on the surface of the molded sheet of polymercomposition of the present invention, which was measured by the use ofX-ray microanalyzer, and

FIG. 2 is a photograph measured with a comparative example.

DESCRIPTION OF THE INVENTION

In following, explanation will be made in more detail.

The radiation-resistant high molecular composition of the presentinvention can be achieved by formulating the halogenated acenaphthyleneand/or condensates thereof and diphenyl ether derivative and/or basiclead compound to the high molecular polymer.

As the high molecular polymers, the radiation resistance beingimprovable, for example, the thermoplastic resins such as polyethylene,polypropylene, polybutene, ethylene-vinyl acetate copolymer,ethylene-ethyl acrylate copolymer, ethylene-propylene copolymer,ethylene-propylene-diene copolymer, ethylene-vinyl chloride copolymer,ethylene-vinyl acetate-grafted vinyl chloride copolymer, ethylene-ethylacrylate-grafted vinyl chloride copolymer, ethylene-propylene-graftedvinyl chloride copolymer, chlorinated polyethylene, chlorinatedpolyethylene-grafted vinyl chloride copolymer, polyamides, acrylicresins, etc., elastomers, polyesters, polyurethanes, thermosettingresins such as epoxy resin, phenol resin, melamine resin, urea resin,etc., butyl rubber, chloroprene rubber,-nitrile rubber, natural rubber,silicone rubber, chlorosulfonated polyethylene, styrene-butadienerubber, styrene-butadiene-acrylonitrile copolymer, polyester-etherelastomer, etc. can be exemplified. Among them, polyolefinic resinsrepresented by polyethylene and polyolefinic elastomers represented byethylenepropylene-diene copolymer are general-purpose polymers havingvarious characteristics excellent in the electric characteristics,chemical resistance, etc. Since the inflammability being a shortcomingthereof can also be improved according to the present invention, theyare the most suitable polymers.

The halogenated acenaphthylene and/or condensates thereof referred to soin the present invention are shown by the following general formula [I]##STR6## (wherein, X, a, b and n are same as above), i.e. compoundshaving at least not less than one of halogen atoms on the aromatic ringsof acenaphthylene. The condensates are those wherein the halogenatedacenaphthene is condensed formally through the Friedel-Craft reaction tobecome multimer with a condensation degree of two or more and,successively, carbon-carbon double bond is formed on benzyl positionthrough dehydrohalogenation reaction.

The bonding pattern of the condensates is an intermolecular bondingbetween carbon on benzyl position of acenaphthylene and carbon on allylposition of another acenaphthylene. As the bonding points for example,##STR7## the like are exemplified, but, besides of these, bondings at 1(or 2), 3'-, 1 (or 2), 4'-, 1 (or 2), 7'-, 1 (or 2), 8'-, etc. areconsiderable.

With regard to those with a bonding degree of three or more, theconstitution unit is allowed to increase by any one of such bondings.The condensates referred to so in the present invention are those with acondensation degree of not more than 10, which are excellent in thecompatibility with resins.

The amount of these halogenated acenaphthylene and/or condensatesthereof to be formulated to the high molecular polymer is preferable tobe 5 to 150 parts by weight per 100 parts by weight of high molecularpolymer in order to secure good radiation resistance at the lower limitand elongation characteristics, pliability, etc. of high molecularcomposition at the upper limit. If under 5 parts by weight, theradiation resistance dose not develop sufficiently and, even ifformulated in amounts of over 150 parts by weight, the weighting effectwould hardly be seen.

Next, the diphenyl ether derivatives referred to so in the presentinvention are compounds represented by the following general formula[II] ##STR8## (wherein, R₁ and R₂ are same as above), or a mixture ofthese.

For example.-, diphenyl ether, monoalkyldiphenyl ether, dialkyldiphenylether, monoalkoxydiphenyl ether, dialkoxydiphenyl ether,phenoxydiphenyl, phenylphenoxydiphenyl, phenoxydiphenyl ether,diphenoxydiphenyl ether, phenoxypheoxydiphenyl, phenoxyphenoxyterphenyl,etc. can be mentioned concretely.

The amount of these diphenyl ether derivatives to be formulated isselected within a range of 1 to 100 parts by weight per 100 parts byweight of halogenated acenaphthylene and/or condensates. The reasons arethat, if under 1 part by weight, the effect to allow the halogenatedacenaphthylene and/or condensates thereof to disperse uniformly into thehigh molecular polymer is insufficient and, on the other hand, that,even if exceeded 100 parts by weight, the weighting effect can hardly beseen.

Next, the basic lead compounds referred to so in the present inventionare compounds selected from lead oxides, lead hydroxides, leadphosphates, lead phosphites, lead carbonates, lead sulfits, leadcarboxylates, lead sulfides, lead borates and lead metaborates or doublesalts containing these as components. Moreover, mixtures of these arealso included. For example, concretely, lead monoxide (PbO), red lead(Pb₃ O₄), white lead (2PbCO₃.Pb(OH)₂), lead dioxide (PbO₂), tribase(ePbO.PbSO₄.H₂ O), basic lead silicate (PbO.H.₂ PbSiO₃), dibasic leadphosphite (2PbO.PbHPO .1/2H₂ O), d-basic lead phthalate (2PbO.Pb(C₈ H₄O₄)), tribasic lead maleate (3PbO.Pb(C₄ H₂ O₄).H₂ O), lead silicateprecipitated together with silica gel (PbSiO₃.mSiO₂), lead salicylate(Pb(C₇ H₅ O₃)₂), lead stearate (Pb(C₁₈ H₃₅ O₂)₂), dibasic lead stearate(2PbO.Pb(C₁₈ H₃₅ O₂)₂), lead naphthenate (Pb(C_(n) H_(2n-1) O₂)₂), leadacetate (Pb(C₂ H₃ O₂ )₂), lead oxalate (PbCrO₄), basic lead sulfite(PbO.PbSO₃), lead phosphate (Pb₃ (PO₄)₂), lead carbonate (PbCO₃), leadmetaborate (Pb(BO₂)₂), lead borate (Pb₃ (BO₄)₂), etc. can be mentioned.

Further, the basic lead compounds used in the present invention arepreferable to be powdery compounds having a specific surface area of atleast 0.1 m² /g determined by BET method.

The reason is that, with compounds having a specific surface area of-notless than 0.1 m² /g, remarkable improvement effect on the hot-waterresistance can be recognized, but, with those having a specific surfacearea of under 0.1 m² /g, the effect on the improvement in hot-waterresistance can hardly seen upon addition and, even if increased theaddition amount, the effect is small.

The upper limit of the specific surface area is not particularlyconfined, but it is around 50 m² /g usually.

The amount of these basic lead compounds to be formulated is selectedwithin a range of 10 to 100 parts by weight per 100 parts by weight ofhalogenated acenaphthylene and/or condensates thereof. The reasons arethat, if under 10 parts by weight, the effect to improve the hot-waterresistance is insufficient and, on the other hand, that, even if over100 parts by weight, the weighting effect would hardly be seen.

The reason why the improvement in the dispersibility of halogenatedacenaphthylene and/or condensates thereof in the high molecular polymerenhances the radiation resistance is not well clear. However, throughthe uniform dispersion, the following two points may result in theinhibition of deterioration of the polymer, so that the radiationresistance would be developed; the acenaphthylene derivatives acteffectively as trap sites of excitation energy generated by theirradiation of radiation to enhance the transfer efficiency of theexcitation energy, and the formed polymer radicals are effectivelycaptured.

The reason is also not well clear that the hot-water resistance of thehigh molecular composition is improved conspicuously by the formulationof basic lead compounds. However, sorption of moisture by hydrogenhalide gas by produced, although in very small amount, by heating orexposure to high-temperature steam is considered to be responsible tothe lowering of the electric characteristics. On the other hand, theformulation of the basic lead compounds results in effective capture ofsaid by produced hydrogen halide gas and formation of water-insolublesalt. consequently, the hot-water resistance is considered to beimproved.

Formulation of Suitable reinforcement agents, extenders, pigments,lubricants, vulcanizing agents, crosslinking assistants, antionidants,ultraviolet absorbers, flame retardation, assistants etc. to thecompositions of the present invention may safely be applicable inappropriate amount within a range not lowering the characteristicsthereof depending on the purpose of use etc.

As a formulating recipe in the present invention, the halogenatedacenaphthylene and/or condensates thereof and the diphenyl etherderivatives and/or basic lead compound are formulated to the highmolecular polymer and then, by heating sufficiently at the time ofkneading, the halogenated acenaphthylene and/or condensates thereof areallowed to melt and disperse uniformly into the high molecular polymer.

Further, it is effective depending on the kind of resins that, whenmolding of these high molecular compositions, free radical-generatingtreatment is given by the chemical crosslinking method comprising ofincorporation of organic peroxides such as dicumyl peroxide etc. andheating, and so-called radiation crosslinking method wherein theionizing radiations such as β-rays, γ-rays, electron beams, etc. areirradiated, and the like to allow the halogenated acenaphthylene and/orcondensates thereof to be grafted onto the high molecular substrate andsimultaneously to give the crosslinking treatment to the high molecularpolymer.

In particular, the utilization of thus crosslinked high molecularcompositions of the present invention for covering materials of electricwires and cables is effective to make them long lives under theenvironment of radiation, so that the value of industrial utilization isvery large.

The crosslinking method in this case is preferable to use organicperoxide compounds as crosslinking agents and to perform undermoisture-free condition, for example, there are methods wherein moltensalt bath, Wood's metal bath, liquid paraffin bath, bath of nonoxidativeinert gas, heated metal tube, etc. are utilized, methods wherein heatingmeans such as high-frequency heating, microwave heating, infraredheating, fluidized bed heating, etc. are used independently or incombination, and the like, when using the high molecular compositions ofthe present invention as the covering materials of electric wires andcables, the method by molten salt bath is preferable and, in moredetail, the molten salt bath having sodium nitrate, potassium nitrateand sodium nitrite as the major components is preferable particularly.

The temperature at the time of crosslinking has only to be over thedecomposition temperature of the organic peroxide crosslinking agentsaforementioned.

Moreover, as a covering method of wires, extrusion according to usualmethods for the covering of the conductors in a desired thickness andthe like can be applied sufficiently.

To the insulated wire cores thus obtained, in some cases protectivesheaths are provided to prevent the external injuries, or, in othercases, a plurality of insulated wire cores aforementioned are collectedto form cable cores and protective sheaths is provided similarly ontosaid cable cores.

With regard to the crosslinking means of this sheath, too, crosslinkedplastics or vulcanized rubbers are provided from the aspect ofmechanical and thermal characteristics. If applying the method of thepresent invention described above at the time of providing the sheathlayer of said crosslinked plastics or vulcanized rubbers, one withcharacteristics further improved can be obtained preferably.

As such sheath materials, vinyl chloride resin, chlorosulfonatedpolyethylene, chloroprene rubber, etc. are applicable. In particular,chlorosulfonated polyethylene is suitable for the purpose of the presentinvention because of its excellent radiation resistance, waterresistance and fire resistance.

In following, the present invention will be further illustrated based onthe examples, but is not confined to these.

EXAMPLE 1 THROUGH 3 AND COMPARATIVE EXAMPLE 1 AND 2

To ethylene-propylene-diene copolymer were added formulating agents togive compositions as shown in Table 1. Besides, the unit of amount ofrespective ingredients formulated in the respective examples below ispart by weight.

After uniformly kneaded all ingredients except the freeradical-generating agent on a hot roll of 160° C., the freeradical-generating agent was added at 20° to 70° C. Then, these wereheated for 30 minutes under pressure using a hot press of 160° C. tomold sheets with a thickness of 1 mm.

Besides, the halogenated acenaphthylene and/or condensates thereof usedin these examples are condensed bromoacenaphthylene compositionspecified as follows:

    ______________________________________                                        Content of bromine                                                                              55.7%                                                       Melting point     125-143° C.                                          Condensate composition                                                        Monomer           19.0%                                                       Dimer             19.5%                                                       Trimer            18.9%                                                       Tetramer to octamer                                                                             42.6%                                                       ______________________________________                                    

The condensate composition was determined by means of high performanceliquid chromatography using a column with an inner diameter of 7.5 mmand a length of 600 mm packed with TSK gel G1000H8 (made by Toyo SodaMfg. Co.).

To the sheets obtained with respective compositions, 200 Mrad of α-raywere irradiated at a dose rate of 0.5 Mrad/hr at room temperature in theair, the mechanical characteristics before and after the irradiationwere determined according to JIS C3005 to estimate the radiationresistance of respective samples. The results are shown in Table 1.

Further, the change of grafting ratio of halogenated acenaphthyleneand/or condensates thereof onto the high molecular polymer before andafter the irradiation of γ-ray was determined by the Soxhlet extractionmethod with tetrahydrofuran, the results obtained are shown in Table 1.

Moreover, the dispersibility of condensed bromoacenaphthylene in thesurface of respective sheets was measured with Brkα line by the use ofX-ray microanalyzer. The dispersibility in the sheet of Example 1 andthat in the sheet of Comparative example 1 are shown in FIG. 1 and FIG.2, respectively. The white dots show the existence of bromine atoms.

                                      TABLE 1                                     __________________________________________________________________________                                       Comparative                                Formulating agent and                                                                          Example           example                                    characteristics  1     2     3     1     2                                    __________________________________________________________________________    Etylene-propylene-diene                                                                        100   100   100   100   100                                  copolymer *1                                                                  Nocrac 224 *2    1.5   1.5   1.5   1.5   1.5                                  Sulfur           0.4   0.4   0.4   0.4   0.4                                  Talc             100   100   100   100   100                                  Zinc white       5     5     5     5     5                                    Antimony trioxide                                                                              11.8  11.8  11.8  11.8                                       Dicumyl peroxide 3     3     3     3     3                                    Condensed bromoacenaphythylene                                                                 45    45    45    45                                         composition                                                                   m-(m-Phenoxyphenoxy)diphenyl                                                                   5                       5                                    Monoalkyldiphenyl ether *3                                                                           5                                                      Dialkyldiphenyl ether *3     5                                                Uniform dispersibility of                                                                      Excel-                                                                              Excel-                                                                              Excel-                                                                              No good                                                                             --                                   brominated acenaphthylene                                                                      lent  lent  lent                                             condensate composition in                                                     sheet                                                                         (Mechanical characteristics)                                                  Initial                                                                            Tensile strength                                                                          0.88  0.76  1.11  0.82  0.88                                      (Kg/mm.sup.2)                                                                 Elongation (%)                                                                            640   695   660   752   765                                  After ir-                                                                          Tensile strength                                                                          0.87  0.87  1.03  0.98  0.98                                 radiation                                                                          (Kg/mm.sup.2)                                                                 Elongation (%)                                                                            145   143   165   70    53                                   (Electric characteristic)                                                                      3.5 × 10.sup.15                                                               4.3 × 10.sup.15                                                               4.6 ×  10.sup.15                                                              3.6 × 10.sup.15                                                               2.6 × 10.sup.15                Volume resistance (Ω-cm) 21° C.)                                 (Grafting ratio of condensed                                                  bromoacenaphthylene composi-                                                  tion) (%)                                                                     Initial          25.2  26.0  25.9  21.4  --                                   After irradiation                                                                              40.4  42.3  41.3  33.6  --                                   __________________________________________________________________________     *1 Made by Japan Synthetic Rubber Co., EP21 (Bonding amount of propylene:     40% by weight).                                                               *2 Made by Oouchi Shinko Co., 2,2,4Trimethyl-1,2-dihydroquinoline             copolymer.                                                                    *3 Number of carbon atoms in alkylmoiety: 16                             

The condensed bromoacenaphthylene composition used in Example 1 through5 and Comparative example 1 through 3 contains as much as 42.6 of thehigh-condensation components of tetra to octamer and the condensationcomposition is high. With the formulation of this composition withoutthe diphenyl ethers to the high molecular polymer, the effect to providethe radiation resistance, which is shown by the fracture elongationafter the irradiation of γ-rays, was small.

On the other hand, the condensed bromoacenaphthylene composition used inExample 6 through 9 and Comparative example 4 through 8 described latercontains as little as 18.4 % of the tetra to actamer and thecondensation composition is low. With the formulation of this, highradiation resistance can be developed stably.

As described above, the effect to provide the radiation resistanceclearly depended on the difference the condensate composition ofcondensed bromoacenaphthylene.

However, as evident from Table 1 and FIG. 1, even when formulated thebrominated acenaphthylene condensates high in the condensationcomposition, by the addition of diphenyl ether derivatives of thepresent invention, the uniform dispersibility thereof was achieved andthe mechanical characteristics after the irradiation of radiation werealso excellent, in particular, the lowering in the elongationcharacteristic became to be suppressed. Whereas, without diphenyl etherderivative (Comparative example 1), the deterioration of mechanicalcharacteristics after the irradiation of radiation was remarkableresulting from the inhomogeneity of dispersibility, as shown in FIG. 2,due to the partial aggregation of the brominated acenaphthylenecondensates. Moreover, in the case of addition of the diphenyl etherderivative along (Comparative example 2), the radiation resistance wanot improved.

On the other hand, the uniform dispersion of condensedbromoacenaphthylene enhanced its grafting before and after γ-rayirradiation. This fact shows effective capture of polymer radicalsgenerated by the γ-ray irradiation as well as the effect to promotetransfer of the excitation energy of irradiated the γ-ray.

Moreover, the addition of diphenyl ether derivatives hardly affectsadversely on the crosslinking of polymer and the electriccharacteristics.

EXAMPLE 4 AND 5 AND COMPARATIVE EXAMPLES 3 AND 4

To polyethylene, the formulating agents were added so as to give thecomposition shown in Table 2. These were kneaded well on a heated rolland the composition thus obtained were molded with press for 30 minutesat 160° C. to prepare sheets with a thickness of 1 mm.

On the respective sheets obtained, the dispersibility of the condensedbromoacenaphthylene initial mechanical characteristics and those afterthe irradiation of 200 Mrad of γ-rays were determined. The results areshown in Table 2.

                                      TABLE 2                                     __________________________________________________________________________                                Comparative                                       Formulating agent and                                                                          Example    example                                           characteristics item                                                                           4    5     3    4                                            __________________________________________________________________________    Polyethylene *4  100  100   100  100                                          Nocrac 300 *5    0.5  0.5   0.5  0.5                                          Dicumyl peroxide 3    3     3    3                                            Antimony trioxide                                                                              11.8 11.8  11.8                                              Condensed bromoacenaphythylene                                                                 45   45    45                                                composition                                                                   m-(m-phenoxyphenoxy)diphenyl                                                                   5               5                                            Monoalkyldiphenyl ether                                                                             5                                                       Uniform dispersibility of                                                                      Excellent                                                                          Excellent                                                                           No good                                                                            --                                           condensed bromoacenaphthylene                                                 in sheet                                                                      (Mechanical characteristics)                                                  Initial                                                                            Tensile strength                                                                          2.31 2.25  1,97 2.30                                              (Kg/mm.sup.2)                                                                 Elongation (%)                                                                            510  495   488  513                                          After ir-                                                                          Tensile strength                                                                          1.82 1.88  1.42 1.37                                         radiation                                                                          (Kg/mm.sup.2)                                                                 Elongation (%)                                                                            170  182   90   55                                           __________________________________________________________________________     *4 Density: 0.920, MI: 1,0                                                    *5 Made by Oouchi Shinko Co., 4,4Thiobis(6-t-butyl-3-methylphenol).      

EXAMPLES 6 THROUGH 9 AND COMPARATIVE EXAMPLE 5 THROUGH 8

The sheets of Table 3 were prepared in the same procedure as describedfor example 1. The molded sheets were exposed to hightemperature steamof 150° C., 4.9kg/cm² for 24 hours. Then hot-water resistance of eachspecimen was estimated by the volume resistance and the dielectricbreakdown voltage. The results, as well as the other results obtained inthe similar manner to example 1 are also shown in Table 3.

Besides, the halogenated acenaphthylene and/or condensates thereof usedin these examples are condensed bromoacenaphthylene compositionspecified as follows:

    ______________________________________                                        Content of bromine                                                                              55.7%                                                       Melting point     125-143° C.                                          Condensate composition                                                        Monomer           17.6%                                                       Dimer             36.0%                                                       Trimer            28.0%                                                       Tetramer to octamer                                                                             18.4%                                                       ______________________________________                                    

The condensate composition was determined by the same method forprevious examples.

                                      TABLE 3 (1)                                 __________________________________________________________________________    Formulating agent and                                                                            Example                                                    characteristics item                                                                             6     7     8     9                                        __________________________________________________________________________    Ethylene-propylene-diene copolymer *1                                                            100   100   100   100                                      Nocrac 224 *2      1.5   1.5   1.5   1.5                                      Sulfur             0.4   0.4   0.4   0.4                                      Talc               100   100   100   100                                      Zinc white         5     5     5     5                                        Stearic acid       1     1     1     1                                        Antimony trioxide  11.8  11.8  11.8  11.8                                     Dicumyl peroxide   3     3     3     3                                        Condensed bromoacenaphthylene                                                                    45    45    45    45                                       White lead         15                                                         Tribase                  15                                                   Litharge                       30                                             Dibasic lead phthalate               10                                       Lead chloride                                                                 Specific surface area of lead                                                                    1.20  1.92  0.34  0.83                                     compound *3                                                                   (Radiation resistance)                                                        Initial                                                                            Tensile strength (Kg/mm.sup.2)                                                              0.87  0.91  0.77  0.80                                          Elongation (%)                                                                              640   670   710   695                                      After ir-                                                                          Tensile strength (Kg/mm.sup.2)                                                              0.86  0.77  0.82  0.92                                     radiation                                                                          Elongation (%)                                                                              145   160   155   145                                      (Fire resistance)                                                             Oxygen index       36.4  34.8  36.0  34.2                                     (Hot-water resistance)                                                        Initial                                                                            Volume resistance (Ω-cm)                                                              4.5 × 10.sup.15                                                               5.1 × 10.sup.15                                                               3.6 ×  10.sup.15                                                              4.2 × 10.sup.15                         Dielectric breakdown                                                                        24.3  24.6  22.9  22.3                                          voltage (kV/mm)                                                          After                                                                              Volume resistance (Ω-cm)                                                              5.1 × 10.sup.15                                                               5.0 × 10.sup.15                                                               2.9 × 10.sup.15                                                               4.5 × 10.sup.15                    exposure                                                                           Dielectric breakdown                                                                        24.8  24.0  22.6  22.8                                          voltage (kV/mm)                                                          __________________________________________________________________________     *1 Made by Japan Synthetic Rubber Co., EP21 (Bonding amount of propylene:     40% by weight).                                                               *2 Made by Oouchi Shinko Co., 2,2,4trimethyl-1,2-dihydroquinoline             copolymer.                                                                    *3 Determined by BET method                                              

                                      TABLE 3 (2)                                 __________________________________________________________________________    Formulating agent and                                                                            Comparative example                                        characteristics item                                                                             5     6     7     8                                        __________________________________________________________________________    Ethylene-propylene-diene copolymer *1                                                            100   100   100   100                                      Nocrac 224 *2      1.5   1.5   1.5   1.5                                      Sulfur             0.4   0.4   0.4   0.4                                      Talc               100   100   100   100                                      Zinc white         5     5     5     5                                        Stearic acid       1     1     1     1                                        Antimony trioxide  11.8  11.8  11.8  11.8                                     Dicumyl peroxide   3     3     3     3                                        Condensed bromoacenaphthylene                                                                    45    45    45    45                                       White lead               3                                                    Tribase                                                                       Litharge                                                                      Dibasic lead phthalate         30                                             Lead chloride                        15                                       Specific surface area of lead                                                                    --    1.20  0.06  1.31                                     compound *3                                                                   (Radiation resistance)                                                        Initial                                                                            Tensile strength (kg/mm.sup.2)                                                              0.82  0.93  1.03  0.87                                          Elongation (%)                                                                              752   660   595   630                                      After ir-                                                                          Tensile strength (kg/mm.sup.2)                                                              0.86  0.90  0.95  0.85                                     radiation                                                                          Elongation (%)                                                                              150   143   141   151                                      (Fire resistance)                                                             Oxygen index       34.8  35.0  34.2                                                                              36.0                                       (Hot-water resistance)                                                        Initial                                                                            Volume resistance (Ω-cm)                                                              4.1 × 10.sup.15                                                               3.7 × 10.sup.15                                                               4.7 ×  10.sup.15                                                              5.5 × 10.sup.15                         Dielectric breakdown                                                                        22.0  22.9  24.7  22.3                                          voltage (kV/mm)                                                          After                                                                              Volume resistance (Ω-cm)                                                              2.8 × 10.sup.10                                                               1.8 × 10.sup.11                                                               3.1 × 10.sup.12                                                               4.8 × 10.sup.11                    exposure                                                                           Dielectric breakdown                                                                        5.8   6.7   8.2   6.5                                           voltage (kV/mm)                                                          __________________________________________________________________________     *1 Made by Japan Synthetic Rubber Co., EP21 (Bonding amount of propylene:     40% by weight).                                                               *2 Made by Oouchi Shinko Co., 2,2,4trimethyl-1,2-dihydroquinoline             copolymer.                                                                    *3 Determined by BET method                                              

EXAMPLE 10 THROUGH 12 AND COMPARATIVE EXAMPLE 9 AND 10

The sheets of Table 4 were prepared in the same procedure as describedfor example 3

The state of respective sheets thus made up was observed, and the gelfraction and heat deformation rate were measured. In addition, the fireresistance, radiation resistance and hot-water resistance were estimatedaccording to Example 6. The results are shown in Table 4.

                                      TABLE 4                                     __________________________________________________________________________                                        Comparative                               Formulating agent and                                                                           Example           example                                   characteristics item                                                                            10    11    12    9     10                                  __________________________________________________________________________    Polyethylene *4   100   100   90    100   90                                  Ethylene-vinylacetate copolymer *5                                                                          10                                              stearic acid      1     1     1     1     1                                   Nocrac 300        0.5   0.5   0.5   0.5   0.5                                 Dicumyl peroxide  3     3     3     3     3                                   Antimony trioxide 10    10    10    10    10                                  Condensed bromoacenaphthylene                                                                   30    30    30    30    30                                  White lead        5           5                                               Tribase                 10                                                    Lead sulfate                              10                                  Specific surface area of lead                                                                   1.20  1.92  1.20  --    --                                  compound (m.sup.2 /g)                                                         Moldability of sheet                                                                            Excellent                                                                           Excellent                                                                           Excellent                                                                           No good *6                                                                          No good *6                          Gel fraction (wt. %) *7                                                                         73.5  74.2  75.0  45.9  51.1                                Heat deformation (%) *8                                                                         13.0  13.9  13.8  43.7  42.4                                (Radiation resistance)                                                        Initial                                                                            Tensile strength (kg/mm.sup.2)                                                             1.87  1.80  2.13  1.37  1.43                                     Elongation (%)                                                                             400   370   380   420   473                                 After ir-                                                                          Tensile strength (kg/mm.sup.2)                                                             1.36  1.33  1.50  0.83  0.88                                radiation                                                                          Elongation (%)                                                                             145   137   130   78    90                                  (Fire resistance)                                                             Oxygen index      28.9  29.4  29.0  27.2  27.4                                (Hot-water resistance)                                                        Initial                                                                            Volume resistance (Ω-cm)                                                             2.2 × 10.sup.16                                                               2.0 × 10.sup.16                                                               7.0 × 10.sup.15                                                               1.4 × 10.sup.16                                                               6.4 × 10.sup.15                    Dielectric breakdown                                                                       31.0  30.5  27.6  30.0  27.9                                     voltage (kV/mm)                                                          After                                                                              Volume resistance (Ω-cm)                                                             2.4 × 10.sup.16                                                               1.8 × 10.sup.16                                                               6.4 × 10.sup.15                                                               7.1 × 10.sup.12                                                               5.0 × 10.sup.11               exposure                                                                           Dielectric breakdown                                                                       30.4  30.5  27.0  13.5  8,3                                      voltage (kV/mm)                                                          __________________________________________________________________________     *4 Density: 0.920, MI: 1.0                                                    *5 Density: 0.940, MI: 2,5, Content of vinylacetate: 19%                      *6 Because of surface burning, smooth sheet could not be obtained.            *7 Determined after immersed for 24 hours at 120° C. in xylene.        *8 Measured after loaded with 3 kg at 120° C.                     

EXAMPLES 13 THROUGH 16

To ethylene-propylene-diene copolymer, the formulating agents were addedso as to get the compositions shown in Table 5.

Sheets were made according to the processing recipe in Example 6 through9 and the estimation of performance of molded sheets were made by themethod in said examples. The results are shown in Table 5.

Besides, with regard to the condensed bromoacenaphthylene composition,one used in Example 13 and 14 in same as in Example 1 and one used inExample 15 and 16 is same as in Example 6.

                                      TABLE 5                                     __________________________________________________________________________    Formulating agent and                                                                            Example                                                    characteristics item                                                                             13    14    15    16                                       __________________________________________________________________________    Ethylene-propylene-diene copolymer *1                                                            100   100   100   100                                      Nocrac 224 *2      1.5   1.5   1.5   1.5                                      Sulfur             0.4   0.4   0.4   0.4                                      Talc               100   100   100   100                                      Zinc white         5     5     5     5                                        Stearic acid       1     1     1     1                                        Antimony trioxide  11.8  11.8  11.8  11.8                                     Dicumyl peroxide   3     3     3     3                                        Condensed bromoacenaphthylene                                                                    45    45    45    45                                       White lead         15                30                                       Tribase                  15                                                   Litharge                       30                                             m-(m-Phenoxyphenoxy)diphenyl                                                                     5           5                                              Monoalkyldiphenyl ether  5           10                                       Specific surface area of lead                                                                    1.20  1.92  0.34  1.20                                     compound (m.sup.2 /g) *3                                                      (Radiation resistance)                                                        Initial                                                                            Tensile strength (kg/mm.sup.2)                                                              0.86  0.88  0.82  0.91                                          Elongation (%)                                                                              630   660   700   675                                      After ir-                                                                          Tensile strength (kg/mm.sup.2)                                                              0.87  0.82  0.80  0.90                                     radiation                                                                          Elongation (%)                                                                              150   155   160   145                                      (Fire resistance)                                                             Oxygen index       34.6  34.4  35.2  35.0                                     (Hot-water resistance)                                                        Initial                                                                            Volume resistance (Ω-cm)                                                              3.9 × 10.sup.15                                                               4.4 ×  10.sup.15                                                              5.0 × 10.sup.15                                                               4.5 × 10.sup.15                         Dielectric breakdown                                                                        24.8  23.0  24.4  23.7                                          voltage (kV/mm)                                                          After                                                                              Volume resistance (Ω-cm)                                                              4.2 × 10.sup.15                                                               4.0 × 10.sup.15                                                               4.6 × 10.sup.15                                                               4.4 × 10.sup.15                    exposure                                                                           Dielectric breakdown                                                                        25.0  22.6  24.1  24.2                                          voltage (kV/mm)                                                          __________________________________________________________________________     *1 Made by Japan Synthetic Rubber Co., EP21 (Bonding amount of propylene:     40% by weight).                                                               *2 Made by Oouchi Shinko Co., 2,2,4trimethyl-1,2-dihydroquinoline             copolymer.                                                                    *3 Determined by BET method.                                             

From foregoing examples, it is understood that the formulation of basiclead compound of the present invention to high molecular compositioncontaining halogenated caenaphthylene and/or condensates thereofrealizes improvement the hot-water remarkable resistance with theexcellent radiation and fire resistance thereof not affected adversely.

Further, in the case of crosslinked polyethylene composition, it isevident that the problems of processibility and heat deformation aresolved in addition to the improvement in the hot-water-resistance andthe formulation is serving also for the improvement in the radiationresistance.

Whereas, evidently, the composition formulated with nonbasic leadcompounds lead such as chloride and lead sulfate, as illustrated inComparative example 8 and 10, hardly have effect on improvement inhot-water resistance, even though they may be increased in partsformulated.

EXAMPLE 17 THROUGH 19 AND COMPARATIVE EXAMPLE 11 THROUGH 13

After the kneading and granulation, the compositions in Example 1, 6 and14 and Comparative example 5 and 6 were extruded for conversing onto atin-plated twisted wire made from soft copper with cross sectional areaof 2 mm² so as the thickness to become 0.8 mm. Then, these werecontinuously vulcanized by heating under the conditions shown in Table 6to give desired electric wires.

To the insulated electric wires thus obtained, 200 Mrad of γ-rays wasirradiated at a dose rate of 0.5 Mrad/hr at room temperature in the air.Further, the insulated electric wires after the γ-ray irradiation wereexposed to high-temperature steam of 150° C. and 4.9 kg/cm² for 24hours.

Of these insulated electric wires before and after the irradiation andafter the exposure to steam, the mechanical and electric characteristicswere estimated. The results are shown in Table 6.

                                      TABLE 6                                     __________________________________________________________________________                    Example         Comparative example                           Item            17   18    19   11    12    13                                __________________________________________________________________________    Composition of insulating                                                                     Example                                                                            Example                                                                             Example                                                                            Compara-                                                                            Compara-                                                                            Compara-                          material        1    6     14   tive exam-                                                                          tive exam-                                                                          tive exam-                                                        ple 5 ple 5 ple 6                             Heat vulcanization condition                                                                  Molten.sup.(1)                                                                     Nitrogen.sup.(2)                                                                    Steam.sup.(3)                                                                      Molten.sup.(1)                                                                      Steam.sup.(3)                                                                       Molten.sup.(1)                                    salt gas        salt        salt                              (Initial values)                                                              Mechanical                                                                            Tensile strength                                                                      0.85 0.80  0.88 0.80  0.65  0.88                              characteristics                                                                       (kg/mm.sup.2)                                                                 Elongation (%)                                                                        520  500   610  530   620   550                               Dielectric breakdown voltage                                                                  27   23    22   25    22    23                                (kV).sup.(4)                                                                  (After irradiation of γ-rays)                                           Mechanical                                                                            Tensile strength                                                                      0.88 0.88  0.85 0.85  0.60  0.87                              characteristics                                                                       (kg/mm.sup.2)                                                                 Elongation (%)                                                                        140  130   150  140   150   140                               (After exposure to steam)                                                     Mechanical                                                                            Tensile strength                                                                      0.55 0.52  0.55 0.45  0.33  0.55                              characteristics                                                                       (kg/mm.sup.2)                                                                 Elongation (%)                                                                        110  110   120  100   90    110                               Withstand voltage test.sup.(5)                                                                Accept-                                                                            Accept-                                                                             Accept-                                                                            Reject-                                                                             Reject-                                                                             Reject-                                           able able  able ed    ed    ed                                __________________________________________________________________________     .sup.(1) Heat medium is inorganic salts with a melting point of               142° C., the main components thereof being sodium nitrate,             potassium nitrate and sodium nitrite. Bath temperature: 200° C.,       Pressure of nitrogen gas: 3 kg/cm.sup.2                                       .sup.(2) Temperature of vulcanization tube: 200° C., Pressure of       nitrogen gas: 5 kg/cm.sup.2                                                   .sup.(3) Temperature of steam: 190° C., Pressure: 12 kg/cm.sup.2       .sup.(4) Into water were immersed 5 m of insulated electric wire and          alternating voltage was charged between conductor and water at a rate of      30 kV/min to determine the voltage when the insulating material was broke     down.                                                                         .sup.(5) After wound 1 m of insulated electric wire after exposure to         steam round metallic mandrel with an outer diameter of 15 mm, this was        immersed into water. When charged alternating voltage for 5 minutes           between conductor and water at a rate of 2.6 kV, one, the insulating          material thereof being not broken was made acceptable.                   

On the contrary to the fact that the wires in Example 17 through 19 areacceptable by the withstand voltage test even after the exposure tosteam, those in Comparative example 11 through 13 were all rejected.Besides, with the wire in Example 17, the determination of breakdownvoltage after the withstand voltage test resulted in 15 kV showing thesufficient tolerance, whereas one in Example 19 showed 6 kV being asomewhat lower result. Therefore, it was made clear that, as the heatvulcanization condition the molten salt was superior to the steam.

EXAMPLE 20 THROUGH 22 AND COMPARATIVE EXAMPLE 14 THROUGH 16

After the kneading and granulation, the compositions in Example 5 and 10and Comparative example 3 and 4 were extruded for covering onto atwisted wire made from soft copper with a cross sectional area of 5.5mm² so as the thickness to become 1 mm. Then, these were continuouslyvulcanized by heating under the conditions shown in Table 7 to givedesired electric wires.

To the insulated electric wires thus obtained, 200 Mrad of γ-ray wasirradiated at a dose rate of 0.5 Mrad/hr at room temperature in the air.Further, the insulated electric wires after the irradiation of γ-raywere exposed to high-temperature steam of 150° C. and 4.9 kg/cm² for 24hours.

Of these insulated electric wires before and after the irradiation andafter the exposure to steam, the mechanical and electric characteristicswere estimated. The results are shown in Table 7.

                                      TABLE 7                                     __________________________________________________________________________                    Example        Comparative example                            Item            20   21   22   14    15    16                                 __________________________________________________________________________    Composition of insulating                                                                     Example                                                                            Example                                                                            Example                                                                            Compara-                                                                            Compara-                                                                            Compara-                           material        5    10   10   tive exam-                                                                          tive exam-                                                                          tive exam-                                                        ple 3 ple 3 ple 4                              Heat vulcanization condition                                                                  Molten.sup.(1)                                                                     Molten                                                                             Steam.sup.(1)                                                                      Steam Molten                                                                              Steam                                              salt salt            salt                                     (Initial values)                                                              Mechanical                                                                            Tensile strength                                                                      1.85 1.77 1.89 1.72  1.70  2.25                               characteristics                                                                       (kg/mm.sup.2)                                                                 Elongation (%)                                                                        400  390  400  370   350   500                                Dielectric breakdown voltage                                                                  29   32   29   22    29    55                                 (kV).sup.(1)                                                                  (After γ-ray irradiation)                                               Mechanical                                                                            Tensile strength                                                                      1.81 1.59 1.55 1.40  1.42  1.30                               characteristics                                                                       (kg/mm.sup.2)                                                                 Elongation (%)                                                                        130  140  130  90    100   20                                 (After exposure to steam)                                                     Mechanical                                                                            Tensile strength                                                                      1.35 1.30 1.27 1.35  1.37  1.35                               characteristics                                                                       (kg/mm.sup.2)                                                                 Elongation (%)                                                                        100  120  120  70    70    20                                 Withstand voltage test.sup.(2)                                                                Accept-                                                                            Accept-                                                                            Accept-                                                                            Reject-                                                                             Reject-                                                                             Reject-                                            able able able ed    ed    ed                                 __________________________________________________________________________     .sup.(1) Same conditions as the footnotes of Table 6.                         .sup.(2) After wound 1 m of insulated electric wire after exposure to         steam round metallic mandrel with an outer diameter of 200 mm, this was       immersed into water. When charged alternating voltage for 5 minutes           between conductor and water at a rate of 3.5 kV, one, the insulating          material thereof being not broken was made acceptable.                   

On the contrary to the fact that the wires in Example 20 through 22 areacceptable by the withstand voltage test even after the exposure tosteam, those in Comparative example 14 through 16 were all rejected.Besides, with the wire in Example 21, the determination of breakdownvoltage after the withstand voltage test resulted in 18 kV showing thesufficient tolerance, whereas one in Example 22 showed 7 kV being asomewhat lower result. Therefore, it was made clear that, as the heatvulcanization condition, the molten salt was superior to the steam.

As described above, the addition of diphenyl ether derivatives and/orbasic lead compounds realizes uniform dispersion of halogenatedacenaphthylene and/or condensates thereof in high molecular polymer andexcellent hot-water resistance of the high molecular compositions.Therefore, because of the stably developed functionality of radiationresistance, the high molecular compositions of the present invention areextremely useful for the construction materials, covering insulationmaterials, packings, sealing materials, ect.

What is claimed is:
 1. An electric wire or cable having a covering of aradiation-resistant high molecular composition comprising a highmolecular polymer, a halogenated acenaphthylene and/or condensatesthereof represented by the following general formula (I): ##STR9##wherein, X indicates a chlorine or bromine atom, a indicates 0 to 2, bindicates 1 to 6 and n indicates an integer not less than 1, and adiphenyl ether derivative represented by the following general formula(II): ##STR10## wherein R₁ and R₂ independently indicate hydrogen,alkyl, alkoxy, phenyl phenoxy, diphenyloxy or terphenyloxy.
 2. Theelectric wire or cable of claim 1, wherein the high molecularcomposition further comprises a basic lead compound.
 3. The electricwire or cable of claim 1, wherein the amount of said halogenatedacenaphthylene and/or condensates thereof is 5 to 150 parts by weightper 100 parts by weight of the high molecular polymer.
 4. The electricwire or cable of claim 1, wherein the amount of said diphenyl etherderivative is 1 to 100 parts by weight per 100 parts by weight of saidhalogenated acenaphthylene and/or condensates thereof.
 5. The electricwire or cable of claim 2, wherein said basic lead compound is leadoxide, lead hydroxide, lead phosphate, lead phosphite, lead carbonate,lead sulfite, lead carboxylate, lead sulfide, lead borate or leadmetaborate or a double salt thereof.
 6. The electric wire or cable ofclaim 2, wherein said basic lead compound is a powder whose specificsurface area is at least 0.1 m² /g.
 7. The electric wire or cable ofclaim 2, wherein the amount of said basic lead compound is 10 to 100parts by weight per 100 parts by weight of said halogenatedacenaphthylene and/or condensates thereof.
 8. The electric wire or cableof claim 1, wherein said high molecular polymer is a resin or elastomerselected from the group of thermoplastic resins, thermosetting resinsand natural or synthetic rubbers.
 9. The electric wire or cable of claim1, wherein the amount of said halogenated acenaphthylene and/orcondensates thereof is 5 to 150 parts by weight per 100 parts by weightof said high molecular polymer.
 10. The electric wire or cable of claim1, wherein the high molecular polymer is a polyolefinic resin orelastomer.
 11. A method of manufacturing the electric wire or cableaccording to claim 1, comprising covering said electric wire or cablewith said radiation-resistance high molecular composition, thencrosslinking said composition with an organic peroxide crosslinkingagent under moisture-free condition.
 12. The method of manufacturingaccording to claim 11, wherein said moisture-free condition is obtainedby the use of a molten salt bath.
 13. The method of manufacturingaccording to claim 12, wherein said molten salt bath contains sodiumnitrate, potassium nitrate and sodium nitrate as major components. 14.The method of manufacturing according to claim 11, wherein the amount ofsaid halogenated acenaphthylene and/or condensates thereof is 5 to 150parts by weight per 100 parts by weight of said high molecular polymer.15. The method of manufacturing according to claim 11, wherein said highmolecular polymer is a polyolefinic resin or elastomer.